bool validTree(TreeNode *root, int minVal, int maxVal){
if (root == NULL){
return true;
}
if (root -> val <= minVal || root -> val >= maxVal){
return false;
}
return validTree(root -> left, minVal, root -> val) && validTree(root -> right, root -> val, maxVal);
}
int main(){
vector<vector<int> > edges = {
{0, 1},
{0, 2},
{0, 3},
{1, 4}
};
cout<<validTree(5, edges)<<endl;
return 0;
}
bool isValidBST(TreeNode *root) {
//每一颗二叉树检查的时候子树都有一个最大值和最小值，具体数值由递归树传递过来
return validTree(root, INT_MIN, INT_MAX);
}
